The present invention relates in general to a magnetic recording and reproducing apparatus for recording and reproducing an information signal on and from a magnetic tape by means of a recording and reproducing system and in particular to a tape cassette loading system used in a magnetic recording and reproducing apparatus for loading and unloading a magnetic tape contained in a tape cassette on and from the recording and reproducing system of the apparatus.
Current magnetic recording and reproducing apparatus which record and reproduce an information signal on and from a magnetic tape such as a video tape recorder are loaded with a magnetic tape in a manner such that the magnetic tape is contained in a tape cassette for ease of handling as well as for protection of the magnetic tape. In order to load the magnetic tape contained in the tape cassette into the recording and reproducing system of the video tape recorder which includes a guide drum on which magnetic heads are carried, a cassette loading system is used for transporting the tape cassette from an eject position to a predetermined loading position defined relative to the position of the guide drum and for wrapping the tape around the guide drum in a predetermined manner. The loading system is used also for disengaging the magnetic tape from the guide drum and for transporting the tape cassette back to the initial eject position for removal of the tape cassette.
There are several types of tape cassettes which are currently sold in the market. One typical example of such a tape cassette is called a "standard size" tape cassette and is used widely in home video tape recorders. The aforementioned standard size tape cassette may have a typical dimension of 188.times.104.times.25 mm, for example, and accommodates a half inch wide magnetic tape wound around a supply reel and a take up reel with such an amount that a few hours of recording time is obtained. The specification for the tape cassette as well as for the recording format on the magnetic tape is standardized in relation to the type of the video tape recorder so that the magnetic tape cassettes produced by different manufacturers can be used as long as the specification matches with the type of the video tape recorder.
Recently, a more compact video tape recorder has been developed so as to realize a portable video tape recorder combined with a television camera and the like. Such a tape cassette has a reduced size so as to decrease the size and weight of the video tape recorder. In order to reduce the size, the compact size tape cassette contains a smaller amount of magnetic tape having a substantially reduced separation between a supply reel and a take up reel. On the other hand, the recording format of the video signal and the audio signal on the tape is identical to that of the "standard size" tape cassette, so that compatibility with the home video tape recorder currently in use is maintained.
Conventionally, such a compact size tape cassette is reproduced by the home video tape recorder by using an adapter having a size identical to the size of the standard size tape cassette into which the compact size tape cassette is accommodated, as the size and construction of the compact size tape cassette do not match with the loading system of the video tape recorder designed for the standard size tape cassette. However, the use of this adapter is cumbersome and indeed inconvenient. Thus, there is a demand for a cassette loading system of a video tape recorder which can handle both the standard size tape cassette and compact size tape cassette.
THe U.S. Pat. application entitled "Tape Cassette Loading System" filed by Mihara et al. based on the Japanese Patent Applications No.253096/1987, No.305165/1987 and No.305164/1987 claiming a priority date of Oct.7, 1987 and the U.S. Pat. application entitled "Tape Cassette Loading System" filed by Harumatsu et al. based on the Japanese Patent application No.260584/1987 claiming a priority date of Oct.15, 1987 disclose a loading system comprising a cassette tray on which a standard size tape cassette and a compact size tape cassette are alternatively placed. The cassette tray is carried by a carriage and is movable in a horizontal direction into and out from the body of the video tape recorder. Further, the cassette tray is carried by an elevating mechanism and is movable in a vertical direction. Thus, the standard size or compact size tape cassette placed on the cassette tray is transported to the inside of the video tape recorder horizontally and then transported vertically to the predetermined loading position.
In order to load the magnetic tape in the tape cassette on the guide drum of the video tape recorder, a tape loading mechanism is further needed which enters into the tape cassette and draws out the magnetic tape from the tape cassette in order to wrap the magnetic tape around the guide drum as well as for engaging a drive mechanism with the take up reel and supply reel of the tape cassette. As the aforementioned tape cassette loading system handles both the standard size tape cassette and the compact size tape cassette, such a loading system should be equally capable of handling the magnetic tape contained in the standard size tape cassette and in the compact size tape cassette. However, the size and shape of a cutout portion formed in the tape cassette for allowing , entrance of the tape loading mechanism is different for the standard size tape cassette and the compact size tape cassette. This means that the tape loading mechanism must be displaced responsive to the type of tape cassette to be loaded. Therefore, there is a need for a tape loading mechanism which can be displaced or shifted responsive to the type of tape cassette to be played.
A conventional video tape recorder uses a light emitting element for detection of the end of the magnetic tape. In the tape cassette loading system as described previously, it is necessary, that the position of such a light emitting element be displaced responsive to the type of tape cassette to be played. Thus, there is a need for a mechanism to move the light emitting element responsive to type of the tape cassette.
Furthermore, the conventional video tape recorder applies a weak brake to the rotation of a supply reel in the tape cassette during the recording or reproducing operation to such an extent that the magnetic tape is applied with a proper amount of tension and slackening of the magnetic tape is eliminated. For this purpose, a brake band the periphery of a reel disk which supports the supply reel of the tape cassette and the rotation of the reel disk is braked. In the aforementioned tape cassette loading system adapted for loading the standard size tape cassette and the compact size tape cassette, there is a problem that the brake band adapted to brake the supply reel of the standard size tape cassette during the recording and reproducing operation of the video tape recorder is excessively slackened during the loading of the compact size tape cassette.